FIELD OF THE INVENTION
The present invention refers to an electrically insulating gas-tight penetration of at least two electrical conductors passing through a metal shell of an exhaust system of an internal combustion engine, in particular a metal shell of an electrically heatable catalytic converter.
Prior art electrically insulating gas-tight penetrations are known in large numbers for the most varied uses.
Due to the consequences resulting from atmospheric pollution, stricter and stricter regulations are being issued to limit exhaust emissions, in particular from motor vehicles. As the demands for the reduction of pollutants in exhausts from vehicles increase, more and more complex systems for exhaust cleaning are being used for internal combustion engines. In particular, electrically heated catalytic converters are being used alongside a three-way catalytic converter for the reduction of pollutant emissions during the cold starting phase of an internal combustion engine. Such a configuration is known, for instance, from International Application WO 92/02714, corresponding to U.S. Pat. No. 5,411,711. The problem with such electrically heated catalytic converters is the electrical penetration of an electrical conductor of a voltage source into the electrically heated catalytic converter. A proposed solution for an electrical penetration is known from International Application WO 94/18442. International Application WO 94/18442 suggests constructing the electrically insulating gas-tight penetration in such a way that it is divided into two sections lying one behind the other. The first section thereof, lying closer to the exhaust system, is constructed to be electrically insulating and temperature-resistant but not quite gas-tight, whereas the second section lying farther away from the exhaust system is constructed as a gas-tight and electrically insulating penetration for lower temperatures. In that known penetration, two electrical conductors pass through the shell adjacent one another.